/Engine/Plugins/Experimental/Mutable/Source/CustomizableObject/Classes/MuCO/CustomizableObject.h
Called to load the reference SkeletalMesh if it needs to be used as a placeholder and it's not loaded.
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category=CustomizableObject) void LoadReferenceSkeletalMeshesAsync()